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Lim, Wang-Jin,Choi, Kyung-Min,Hwang, Se Young 한국미생물 · 생명공학회 1993 Journal of microbiology and biotechnology Vol.3 No.4
A novel system has been developed to produce δ-aminolevulinic acid (ALA) using the intact cells of late logarithmic phase of Rhodocyclus gelatinosus KUP-74. The system was shown optimum yield of extracellular ALA under a condition of anaerobic light irradiation (4 Klux) at 30℃ with no variation in cell mass. The rate of extracellular ALA formation was stimulated by low doses of either C_4 or C_5 ALA biosynthetic precursors, where 5 mM (C_4) and 3 mM (C_5) of each precursors were appeared to generate the maximum rates of 3.3 and 4.0 nmoles of ALA per 0.35 ㎎ cells per hr, respectively. Half-life of the system was 10 hr in a sense of an ability of portage transport of L-glutamate, and sequential dose of this compound was resulted in promising recovery of the ALA.
Wang, Guanlin,Lim, Do-Seon,Choi, Baik-Dong,Park, Jin-Ju,Jeong, Soon-Jeong,Kim, Jin-Soo,Kim, Jae-Duk,Park, Jung-Su,Kim, Eung-Kwon,Kim, Byung-Hoon,Ham, Joo-Hyun,Jeong, Moon-Jin The Korean Society for Integrative Biology 2011 Animal cells and systems Vol.15 No.2
Secretory leukocyte protease inhibitor (SLPI) plays an important role in promoting the invasion and metastasis of a range of cancer cells. However, there are no reports of the expression and function of SLPI in oral carcinoma cells. In this study, the oral carcinoma cell line KB was used to determine whether SLPI affects the proliferation, migration and invasion of oral carcinoma cells. RT-PCR and Western blotting revealed high levels of endogenous SLPI expression in KB cells as well as a strong increase in SLPI secretion after wounding compared to immortalized normal oral keratinocytes (INOK). The wound healing assay revealed more migration of KB cells than INOK cells, and the SLPI treatment increased the migration of KB cells. KB cell proliferation was increased significantly by the SLPI protein but decreased by SLPI-siRNA. SLPI strongly increased the migration and invasion of KB cells. On the other hand, SLPI-siRNA decreased the migration and invasion of KB cells. This suggests that SLPI plays an important role in the metastasis of oral carcinoma cells.
Lim, Wang Jin 한국농화학회 1991 Applied Biological Chemistry (Appl Biol Chem) Vol.34 No.4
Six stains of methylotrophic yeast were examined for production of L-methionine-enriched cells. Candida boidinii (Kloeckera sp.) No. 2201, which accumulated 0.54 ㎎/g-dry cell weight (DCW) of free L-methionine (pool methionine), was selected as the parental strain for breeding L-methionine-enriched mutants. Ethionine-resistant mutants derived from the strain by W irradiation. A mutant strain, E500-78, which was resistant to 500㎍/㎖ of DL-ethionine, accumulated 6.02㎎/g-DCW of pool methionine. The culture conditions for mutannt strain E500-78 to increase pool methionine accumulation were optimized. The mutant strain accumulated 8.80 ㎎/g-DCW of pool methionine and contained 16.02 ㎎/g-DCW total methionine. L-methionine-enriched cells production of mutant strain E50078 was greatly improved by the control of pH and by feeding of methanol and other medium components during cultivation in a jar fermentor. Under the optimal conditions, 38.5g (as dry weight) of cells and 282 ㎎ of pool methionine per ℓ of culture broth were obtained after 11 days of cultivation. With limited methanol in continuous cultivation, pool methionine productivity reached a maximum value of 1.14 ㎎/ℓ/h at a dilution rate of 0.05 h^(-1). The effects of an ethionine-resistant mutation in a methylotrophic yeast, Candida boidinii, were studied. In mutant strain E500-78 (ethionine-resistant), SAM synthetase activity was low and was only slightly repressed by L-methionine. Formyltetrahydrofolate synthetase and serine hydroxymethyltransferase were involved in synthesis of the methyl group of L-methionine. The activities of the methyl group transferring enzymes and homocysteine transmethylation were repressed by L-methionine in the wild type strain, but not in the mutant. The activities of the methyl group transferring enzymes were markedly stimulated when the mutant was grown in methanol medium.
Lim, Hyun Kook,Jung, Won Sang,Ahn, Kook Jin,Won, Wang Youn,Hahn, Changtae,Lee, Seung Yup,Kim, InSeong,Lee, Chang Uk American College of Neuropsychopharmacology 2012 Neuropsychopharmacology Vol.37 No.3
Previous studies have shown an association between late-onset depression (LOD) and cognitive impairment in older adults. However, the neural correlates of this relationship are not yet clear. The aim of this study was to investigate the differences in both cortical thickness and subcortical volumes between drug-naive LOD patients and healthy controls and explore the relationship between LOD and cognitive impairments. A total of 48 elderly, drug-naive patients with LOD and 47 group-matched healthy control subjects underwent 3T MRI scanning, and the cortical thickness was compared between the groups in multiple locations, across the continuous cortical surface. The subcortical volumes were also compared on a structure-by-structure basis. Subjects with LOD exhibited significantly decreased cortical thickness in the rostral anterior cingulate cortex, the medial orbitofrontal cortex, dorsolateral prefrontal cortex, the superior and middle temporal cortex, and the posterior cingulate cortex when compared with healthy subjects (all p<0.05, false discovery rate corrected). Reduced volumes of the right hippocampus was also observed in LOD patients when compared with healthy controls (p<0.001). There were significant correlations between memory functions and cortical thickness of medial temporal, isthmus cingulate, and precuneus (p<0.001). This study was the first study to explore the relationships between the cortical thickness/subcortical volumes and cognitive impairments of drug-naive patients with LOD. These structural changes might explain the neurobiological mechanism of LOD as a risk factor of dementia.
Lim, S-H,Choi, S A,Lee, J Y,Wang, K-C,Phi, J H,Lee, D-H,Song, S H,Song, J H,Jin, X,Kim, H,Lee, H J,Lim, I,Kim, S U,Kim, S-K Nature America, Inc. 2011 Cancer gene therapy Vol.18 No.11
The prognosis of medulloblastoma has improved significantly because of advances in multi-modal treatments; however, metastasis remains one of the prognostic factors for a poor outcome and is usually associated with tumor recurrence. We evaluated the migratory potential and therapeutic efficacy of genetically engineered human neural stem cells (NSCs) that encode a prodrug enzyme in the subdural medulloblastoma model. We genetically modified HB1.F3 (F3) immortalized human NSCs to express rabbit carboxylesterase (rCE) enzyme, which efficiently converts the prodrug CPT-11 (Irinotecan) into an active anti-cancer agent (SN-38). To simulate clinical metastatic medulloblastomas, we implanted human medulloblastoma cells into the subdural spaces of nude mice. rCE expressing NSCs (F3.rCE) were labeled with fluorescence magnetic nanoparticle for in vivo imaging. The therapeutic potential of F3.rCE was confirmed using a mouse subdural medulloblastoma model. The majority of intravenously (i.v.) injected, F3.rCE cells migrated to the subdural medulloblastoma site and a small number of F3.rCE cells were found in the lungs, pancreas, kidney and liver. Animals that received F3.rCE cells in combination with prodrug CPT-11 survived significantly longer (median survival: 142 days) than control mice that received F3.rCE cells only (median survival: 80 days, P<0.001) or CPT-11 only (median survival: 118 days, P<0.001). In conclusion, i.v. injected F3.rCE NSCs were able to target subdural medulloblastomas and demonstrate therapeutic efficacy. Our study provides data that supports further investigation of stem-cell-based gene therapy against metastatic medulloblastomas.
Wang, Xun,Ji, Sang Chun,Jeon, Heung Jin,Lee, Yonho,Lim, Heon M. National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.24
<P><B>Significance</B></P><P>Most sRNAs of <I>Escherichia coli</I> function at the 5′ end of the target RNA. Binding of sRNA to the 5′ end of the target RNA induces a ribosome-free zone that causes molecular events such as target RNA degradation and Rho-termination. Results from this study show that Spot 42 enhances Rho-termination at the end of the <I>galT</I> gene, demonstrating for the first time that sRNA could function at the 3′ end of the target RNA. The region where Spot 42 binds overlaps with two other functional cis-acting sites: the ribosome-binding site for <I>galK</I> and the cytosine-rich, guanine-poor region known as the Rho-binding site, suggesting a unique molecular mechanism to enhance Rho-termination occurring at a cistron junction in a multicistronic operon.</P><P>The <I>Escherichia coli gal</I> operon has the structure <I>Pgal-galE-galT-galK-galM</I>. During early log growth, a gradient in gene expression, named type 2 polarity, is established, as follows: <I>galE > galT > galK > galM</I>. However, during late-log growth, type 1 polarity is established in which <I>galK</I> is greater than <I>galT</I>, as follows: <I>galE > galK > galT > galM</I>. We found that type 2 polarity occurs as a result of the down-regulation of <I>galK</I>, which is caused by two different molecular mechanisms: Spot 42-mediated degradation of the <I>galK-</I>specific mRNA, mK2, and Spot 42-mediated Rho-dependent transcription termination at the end of <I>galT</I>. Because the concentration of Spot 42 drops during the transition period of the polarity type switch, these results demonstrate that type 1 polarity is the result of alleviation of Spot 42-mediated <I>galK</I> down-regulation. Because the Spot 42-binding site overlaps with a putative Rho-binding site, a molecular mechanism is proposed to explain how Spot 42, possibly with Hfq, enhances Rho-mediated transcription termination at the end of <I>galT</I>.</P>
Controlled Folding of Single Crystal Graphene
Wang, Bin,Huang, Ming,Kim, Na Yeon,Cunning, Benjamin V.,Huang, Yuan,Qu, Deshun,Chen, Xianjue,Jin, Sunghwan,Biswal, Mandakini,Zhang, Xu,Lee, Sun Hwa,Lim, Hyunseob,Yoo, Won Jong,Lee, Zonghoon,Ruoff, Rod American Chemical Society 2017 Nano letters Vol.17 No.3
<P>Folded graphene in which two layers are stacked with a twist angle between them has been predicted to exhibit unique electronic, thermal, and magnetic properties. We report the folding of a single crystal monolayer graphene film grown on a Cu(111) substrate by using a tailored substrate having a hydrophobic region and a hydrophilic region. Controlled film delamination from the hydrophilic region was used to prepare macroscopic folded graphene with good uniformity on the millimeter scale. This process was used to create many folded sheets each with a defined twist angle between the two sheets. By identifying the original lattice orientation of the monolayer graphene on Cu foil, or establishing the relation between the fold angle and twist angle, this folding technique allows for the preparation of twisted bilayer graphene films with defined stacking orientations and may also be extended to create folded structures of other two-dimensional nanomaterials.</P>